Here is the situation. I find that when using PETG I rarely use the cooling fan. Especially for larger parts since layer bonding is more important for me.
I do find however that if I use the fan full on for the last layer of a dense support then back off for the first layer of the part that goes over the dense support I get very good support removal.

My idea would be to have the option of having the fan come on or ramp up to a selected speed for the top layer of dense support but only while it is printing the actual support and not for the entire layer of the print.

I would find this useful for PETG and ABS. If you cool that last layer of dense support then you don't get quite as much adhesion from the layer going on top of it make separation better.

Thanks for this is a very specific feature request. Our team will be keeping an eye on this. Can you think of any other areas/feature types that would benefit from fan setpoints being feature specific? This could introduce a whole new level of control for users when making custom material profiles for their printers.

"A bird does not sing because it has an answer. It sings because it has a song."